i would also keep the first one. but it's all really up to you whether or not you want to part with the fish or not. chose one that you will not regret keeping, if that makes sense. it is awkward refunding people for retracting a sale offer though, but im sure it's all understandable. if blue and orange makes you happy keep it.
customers do like options: 1) offer the other male instead, and note to the interested party that he is a sibling. 2) if not interested, refund money (of course if you're willing to part with blue/orange, then this whole convo is moot).
that girl has excellent caudal spread. wish that dorsal were a bit wider, but what are you gonna do with a plakat?
she and the female behind her are gorgeous though.